Please refer to FIG. 1 for a conventional sinker of circular knitting machines for pile fabrics. The conventional sinker 31 comprises a nose section 32, support surface 33 being a horizontal surface disposed on the nose section 32, and when the sinker 31 draws back in the final step of the knitting process, the knitting needle 34 pulls the bottom yarn and the binding yarn of a yarn loop 35 down. Since the support surface 33 does not have an inclined angle it is difficult to maintain the angle of a plating loop when the yarn loop falls. In other words, the angle of the plating loop is changed very easily when the yarn loop falls, and thus will cause low quality of fabrics.
Further, the sinker cylinder containing the sinker is rotated at a high speed for knitting. Therefore, the sinker moves back and forth in the driving path of the cam during high-speed rotation. When the sinker cylinder rotates at a high speed, a centrifugal force is produced to give the sinker a large outwards swinging force towards the exterior of the circular knitting machine, such that a protruded plate cannot loop smoothly along the driving path. The contact surface and contact angle of the protruded plate in the driving path form several stress focal points which are worn repeatedly by the centrifugal force. The wear between the sinker and cam shortens their lifetime, and also increases the cost of manufacture which in turn is passed onto the consumer. Furthermore, the sinker cylinder contains thousands of sinkers, operators have to examine and replace them frequently, thus seriously affecting productivity.
It is necessary to improve the shortcomings of the aforementioned circular knitting machine which is not cost-effective or efficient. The design of the present invention can overcome the foregoing shortcomings and improvements upon the prior art.